Now it`s all sorted, can I throw in my memory from a case involving lifting slings which failed,the kind you see on a travel-lift. They failed due to a botched non factory repair,dropping the boat from a considerable height, with owner onboard. But, what was discussed was that the ways the sling ends are brought together or attached can have considerable effect on the rated lifting capacity. FWIW.
2005 Integrity 386 "Sojourn"